1. Field
Embodiments of the present invention relate to an electric brake system for vehicles having a simple configuration, providing a stable pedal feel during braking and enabling accurate pressure control.
2. Description of the Related Art
Brake systems are necessarily mounted in vehicles. In recent years, a variety of systems to obtain stronger and more stable braking force have been suggested. Examples of brake systems include anti-lock brake systems (ABSs) to prevent slippage of wheels during braking, brake traction control systems (BTCSs) to prevent slippage of driving wheels during sudden acceleration of vehicles, and vehicle dynamic control systems (VDCs) to stably maintain a driving state of vehicles by controlling a brake hydraulic pressure through a combination of an anti-lock brake system with a brake traction control system.
These electronically-controlled brake systems include a plurality of solenoid valves to control a brake hydraulic pressure transferred to the hydraulic brake mounted on the wheel of vehicles, a pair of a low-pressure accumulator and a high-pressure accumulator to temporarily store oil escaped from the hydraulic brake, a motor and a pump to forcibly pump the oil of the low-pressure accumulator, a plurality of check valves to prevent reverse flow of the oil, and an ECU to control driving of the solenoid valve and the motor. These components are compactly present in hydraulic blocks made of aluminum.
FIG. 1 is a sectional view illustrating a check valve used for a conventional electronically controlled brake system. For example, the check valve mounted in a passage between a suction part of the pump and the low-pressure accumulator prevents transfer of oil from a master cylinder to the low-pressure accumulator and prevents transfer of oil from a wheel cylinder to the suction part of the pump during operation of the pump by motor driving.
A structure of this brake system is disclosed in Korean Patent No. 1090910. According to the patent document, the brake system fills a high-pressure and/or low-pressure accumulator with a hydraulic pressure by operating a motor and a pump, and increases, decreases, maintains or controls the hydraulic pressure by opening and closing an electronic solenoid valve, thus disadvantageously having a complicated structure.
In addition, since a predetermined gap is present between an input load to pressurize a master cylinder according to a pedal effort of a brake pedal, and the master cylinder, a pedal stroke free region corresponding to the gap during non-operation of a system is formed, a driver disadvantageously has no braking feel, driver convenience suffers and safety issues may arise. In addition, pedal feel is disadvantageously deteriorated.